The project goal is to develop a simple, low cost instrumentation system for objectively evaluating low back pain (LBP) patients. There is a need for methods to objectively assess LBP patients, both as an initial evaluation of injury, and a measure of progress in treatment and rehabilitation. Despite the well documented costs of LBP, no more than fifty percent of LBP patients receive a definite diagnosis. Implementation of the proposed instrument system will provide objective physical measurements based on the Flexion Relaxation Phenomenon or FRP. The FRP characterizes the cessation of back extensor muscle activity when the trunk is flexed fully forward, as measured by surface EMG (electromyograph) and range-of-motion device (inclinometer). It has been shown that patients who are suffering from low back pain exhibit significantly different FRP profiles than normals. Phase I will concern the development of an instrument system to measure the FRP clinically. Device implementation will be accomplished by increasing the functionality of the Fasstech Synergy, an EMG system recently developed by the applicant organization. To demonstrate the feasibility of using the FRP with LBP patients, a clinical pilot study will be conducted on a select group of patients. PROPOSED COMMERCIAL APPLICATION: A successful instrument system for functional analysis of the back would be equivalent in cost and operation to an in-office ECG. Such a system has significant marketability to physicians, group practices ,hospitals, IMEs and insurers concerned with objective evaluations of LBP for treatment justifications and documentation of therapeutic progress.